Skip to content

Creatinine Clearance (Serum-Based)

Published: August 9, 2026Updated: August 16, 2026

This test measures how well your kidneys filter waste products from your blood, using your serum creatinine level and urine flow. It helps assess kidney function and overall kidney health.

Quick summary

["A key measure of kidney function and filtration efficiency."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
35966-1
Short code
CT Elbow-L
Synonyms
CT Elbow-L
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test to check if your kidneys are working properly, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also used before surgeries, to monitor chronic kidney disease, or to evaluate kidney function in people with diabetes or high blood pressure.

How Is the Test Performed?

You’ll provide a blood sample (serum) and a urine sample. Blood is drawn from a vein, usually in your arm. The urine sample is collected over a set period (often 24 hours). Your doctor will guide you on how to properly collect the urine sample to ensure accurate results.

What Do the Results Mean?

Results are compared to your body size and overall health. Lower than expected values might suggest overhydration or errors in urine collection. Higher values could indicate kidney problems, dehydration, or other conditions affecting fluid balance.

Common Causes of Abnormal Results

Abnormal creatinine clearance can result from kidney disease, dehydration, heart failure, or conditions that affect blood flow to the kidneys. It may also be influenced by medications, muscle mass, or certain health conditions like diabetes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Clearance

Frequently asked questions

What is creatinine clearance, and how is it different from a simple blood creatinine test?
Creatinine clearance measures how well your kidneys filter creatinine—a waste product from muscle metabolism—from your blood. Unlike a simple blood creatinine test, which only checks your blood levels, clearance combines blood and urine results to estimate kidney function over time.
Does creatinine clearance require a 24-hour urine collection?
Yes, a 24-hour urine collection is typically needed to accurately measure creatinine clearance. This involves collecting all urine over 24 hours. Some labs may use a simplified method with a single urine sample, but results may be less precise.
Can I take medications or eat certain foods before this test?
Generally, you can eat and drink normally unless instructed otherwise. Avoid excessive fluids or certain medications that might affect kidney function, such as nonsteroidal anti-inflammatory drugs (NSAIDs). Always follow your doctor’s specific instructions for your test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy